Sounds like maybe it's only running on one cylinder, until you get to 3000rpm and then it sounds like the dead cylinder is trying to fire some. Does it pick up rpm on it's own when you hear that sound?
See if one pipe is a lot cooler than the other, have to check toward the front because the exhaust mixes in the 'goat's belly' just ahead of the mufflers.
Could try pulling both plug wires from one cylinder. If it starts but there's no change in power, you have one cyl not firing. If it doesn't start, the other cylinder is the one with the problem.
Another test, but a bit tricky to do sometimes ... the cylinder short test. You remove a plug wire, then with the engine idling, you touch the wire back onto the plug. If the cylinder is firing, the idle will change. No change = dead cylinder. Except on this engine, we have two plug wires per cylinder, so pull both wires, then touch one back to the plug. The big trick is not getting the chit shocked out of you.
Not sure I'm hearing chain tensioners. I think what I heard could be the problem cylinder trying to fire. But it also sounds like what I heard when I had a sticky valve, which is also a possibility on yours. I hear a lot better when I can stand beside the engine.
If it is a cylinder misfiring, it could also be a fuel problem instead of spark.